The present invention relates to a process making it possible to obtain a multipoint light guide, while giving the same a particular shape. It also relates to the products obtained according to this process.
Multipoint light guides of the type in question are formed from well-ordered optical fiber groups. They are mainly used for image transmission purposes, each optical fiber transmitting an elementary point of said images.
These groups or bundles of fibers have numerous applications. In particular, they can be used in the medical field and particularly for endoscopy associated with an entry optics. They can also be used in the electronics and display fields, particularly in the form of optical coupling wafers used e.g. for correcting the curvature of images, in order to obtain a planar image from a cathode ray tube screen or to ensure the connection between a planar persistent screen and the curved photocathode of an image amplifier.
Apart from their use for the transmission of images, as a function of their shapes, these multipoint light guides can also be used for increasing or decreasing the size of images. Image enlargers or reducers are known constituted by well-ordered optical fibers in the form of a conical bundle, whereof the entry diameter and the exit diameter characterize the enlargement or reduction of said means.
The various multipoint light guide types described hereinbefore are generally produced with glass or silica optical fibers, said materials having good optical transmission characteristics (transparency). However, these optical fibers suffer from the disadvantages of being expensive, heavy and relatively inflexible.
The known glass fiber light guides are generally produced either directly by an assembly of well-ordered optical fibers followed by hot, pressurized compacting, or by an assembly of elementary groups of optical fibers obtained by successive drawing or stretching operations.
These processes for the production of light guides suffer from a certain number of disadvantages and particularly their relatively complex and costly realization. For example, the use of glass fibers requires a high working temperature exceeding 600.degree. C. When compacting under pressure between the two parts of a mold, difficulties occur at the junction between these two parts. For the production of image reducers, it is necessary to draw a group of fibers and remove a portion of the drawing cone. Moreover, these processes significantly limit the applications of the multipoint light guides obtained.